Achild, who is 45 m from the bank of a river, is being carried downstream by the river's swift current of 1.0 m/s. as the child passes a lifeguard on the river's bank, the lifeguard starts swimming in a straight line (fig. 3–46) until she reaches the child at a point downstream. if the lifeguard can swim at a speed of 2.0 m/s relative to the water, how long does it take her to reach the child? how far downstream does the lifeguard intercept the child?